Navigation at sea.--The Pleiades.--The pole-star.--Nebulæ--Temporary stars.--Galileo.--The planet of 1898.--How to make a sun-dial.--Photography in astronomy.--Time standards of the world.--Motions of the earth's pole.--Saturn's rings.--The heliometer.--Occultations.--Mounting great telescopes.--The astronomer's pole.--The moon hoax.--The sun's destination